r216619 - Allow adding dll attributes on certain redecls with a warning if the decl hasn't been used yet (PR20746)
Hans Wennborg
hans at chromium.org
Thu Sep 4 10:36:26 PDT 2014
On Thu, Sep 4, 2014 at 10:33 AM, Reid Kleckner <rnk at google.com> wrote:
> Can we merge this to 3.5, or are we done merging patches?
3.5-final was tagged a few days ago. I'd be fine with merging this for
3.5.1, though.
> On Wed, Aug 27, 2014 at 2:27 PM, Hans Wennborg <hans at hanshq.net> wrote:
>>
>> Author: hans
>> Date: Wed Aug 27 16:27:40 2014
>> New Revision: 216619
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=216619&view=rev
>> Log:
>> Allow adding dll attributes on certain redecls with a warning if the decl
>> hasn't been used yet (PR20746)
>>
>> This shouldn't really be allowed, but it comes up in real code (see PR).
>> As
>> long as the decl hasn't been used there's no technical difficulty in
>> supporting
>> it, so downgrade the error to a warning.
>>
>> Differential Revision: http://reviews.llvm.org/D5087
>>
>> Modified:
>> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> cfe/trunk/lib/Sema/SemaDecl.cpp
>> cfe/trunk/test/Sema/dllexport.c
>> cfe/trunk/test/Sema/dllimport.c
>> cfe/trunk/test/SemaCXX/dllexport.cpp
>> cfe/trunk/test/SemaCXX/dllimport.cpp
>>
>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=216619&r1=216618&r2=216619&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Wed Aug 27
>> 16:27:40 2014
>> @@ -2133,6 +2133,9 @@ def warn_attribute_invalid_on_definition
>> InGroup<IgnoredAttributes>;
>> def err_attribute_dll_redeclaration : Error<
>> "redeclaration of %q0 cannot add %q1 attribute">;
>> +def warn_attribute_dll_redeclaration : Warning<
>> + "redeclaration of %q0 should not add %q1 attribute">,
>> + InGroup<DiagGroup<"dll-attribute-on-redeclaration">>;
>> def err_attribute_dllimport_function_definition : Error<
>> "dllimport cannot be applied to non-inline function definition">;
>> def err_attribute_dll_deleted : Error<
>>
>> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=216619&r1=216618&r2=216619&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
>> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Wed Aug 27 16:27:40 2014
>> @@ -5075,7 +5075,7 @@ static void checkDLLAttributeRedeclarati
>> NewDecl = NewTD->getTemplatedDecl();
>>
>> if (!OldDecl || !NewDecl)
>> - return;
>> + return;
>>
>> const DLLImportAttr *OldImportAttr = OldDecl->getAttr<DLLImportAttr>();
>> const DLLExportAttr *OldExportAttr = OldDecl->getAttr<DLLExportAttr>();
>> @@ -5092,13 +5092,30 @@ static void checkDLLAttributeRedeclarati
>> // Implicitly generated declarations are also excluded for now because
>> there
>> // is no other way to switch these to use dllimport or dllexport.
>> bool AddsAttr = !(OldImportAttr || OldExportAttr) && HasNewAttr;
>> +
>> if (AddsAttr && !IsSpecialization && !OldDecl->isImplicit()) {
>> - S.Diag(NewDecl->getLocation(), diag::err_attribute_dll_redeclaration)
>> - << NewDecl
>> - << (NewImportAttr ? (const Attr *)NewImportAttr : NewExportAttr);
>> + // If the declaration hasn't been used yet, allow with a warning for
>> + // free functions and global variables.
>> + bool JustWarn = false;
>> + if (!OldDecl->isUsed() && OldDecl->getDeclContext()->isFileContext())
>> {
>> + auto *VD = dyn_cast<VarDecl>(OldDecl);
>> + if (VD && !VD->getDescribedVarTemplate())
>> + JustWarn = true;
>> + auto *FD = dyn_cast<FunctionDecl>(OldDecl);
>> + if (FD && FD->getTemplatedKind() == FunctionDecl::TK_NonTemplate)
>> + JustWarn = true;
>> + }
>> +
>> + unsigned DiagID = JustWarn ? diag::warn_attribute_dll_redeclaration
>> + : diag::err_attribute_dll_redeclaration;
>> + S.Diag(NewDecl->getLocation(), DiagID)
>> + << NewDecl
>> + << (NewImportAttr ? (const Attr *)NewImportAttr : NewExportAttr);
>> S.Diag(OldDecl->getLocation(), diag::note_previous_declaration);
>> - NewDecl->setInvalidDecl();
>> - return;
>> + if (!JustWarn) {
>> + NewDecl->setInvalidDecl();
>> + return;
>> + }
>> }
>>
>> // A redeclaration is not allowed to drop a dllimport attribute, the
>> only
>>
>> Modified: cfe/trunk/test/Sema/dllexport.c
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/dllexport.c?rev=216619&r1=216618&r2=216619&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/Sema/dllexport.c (original)
>> +++ cfe/trunk/test/Sema/dllexport.c Wed Aug 27 16:27:40 2014
>> @@ -39,8 +39,13 @@ __declspec(dllexport) extern int GlobalR
>> int GlobalRedecl2;
>>
>> extern int GlobalRedecl3; //
>> expected-note{{previous declaration is here}}
>> +int useGlobalRedecl3() { return GlobalRedecl3; }
>> __declspec(dllexport) extern int GlobalRedecl3; //
>> expected-error{{redeclaration of 'GlobalRedecl3' cannot add 'dllexport'
>> attribute}}
>>
>> + extern int GlobalRedecl4; //
>> expected-note{{previous declaration is here}}
>> +__declspec(dllexport) extern int GlobalRedecl4; //
>> expected-warning{{redeclaration of 'GlobalRedecl4' should not add
>> 'dllexport' attribute}}
>> +
>> +
>> // External linkage is required.
>> __declspec(dllexport) static int StaticGlobal; //
>> expected-error{{'StaticGlobal' must have external linkage when declared
>> 'dllexport'}}
>>
>> @@ -86,11 +91,18 @@ __declspec(dllexport) void redecl3();
>> void redecl3() {}
>>
>> void redecl4(); // expected-note{{previous
>> declaration is here}}
>> +void useRedecl4() { redecl4(); }
>> __declspec(dllexport) void redecl4(); // expected-error{{redeclaration of
>> 'redecl4' cannot add 'dllexport' attribute}}
>>
>> void redecl5(); // expected-note{{previous
>> declaration is here}}
>> +void useRedecl5() { redecl5(); }
>> __declspec(dllexport) inline void redecl5() {} //
>> expected-error{{redeclaration of 'redecl5' cannot add 'dllexport'
>> attribute}}
>>
>> +// Allow with a warning if the decl hasn't been used yet.
>> + void redecl6(); // expected-note{{previous
>> declaration is here}}
>> +__declspec(dllexport) void redecl6(); // expected-warning{{redeclaration
>> of 'redecl6' should not add 'dllexport' attribute}}
>> +
>> +
>> // External linkage is required.
>> __declspec(dllexport) static int staticFunc(); //
>> expected-error{{'staticFunc' must have external linkage when declared
>> 'dllexport'}}
>>
>>
>> Modified: cfe/trunk/test/Sema/dllimport.c
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/dllimport.c?rev=216619&r1=216618&r2=216619&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/Sema/dllimport.c (original)
>> +++ cfe/trunk/test/Sema/dllimport.c Wed Aug 27 16:27:40 2014
>> @@ -64,9 +64,16 @@ int GlobalRedecl2c __attribute__((dllimp
>> __declspec(dllimport) extern int GlobalRedecl3; //
>> expected-note{{previous declaration is here}} expected-note{{previous
>> attribute is here}}
>> extern int GlobalRedecl3; //
>> expected-warning{{'GlobalRedecl3' redeclared without 'dllimport' attribute:
>> previous 'dllimport' ignored}}
>>
>> +// Adding an attribute on redeclaration.
>> extern int GlobalRedecl4; //
>> expected-note{{previous declaration is here}}
>> +int useGlobalRedecl4() { return GlobalRedecl4; }
>> __declspec(dllimport) extern int GlobalRedecl4; //
>> expected-error{{redeclaration of 'GlobalRedecl4' cannot add 'dllimport'
>> attribute}}
>>
>> +// Allow with a warning if the decl hasn't been used yet.
>> + extern int GlobalRedecl5; //
>> expected-note{{previous declaration is here}}
>> +__declspec(dllimport) extern int GlobalRedecl5; //
>> expected-warning{{redeclaration of 'GlobalRedecl5' should not add
>> 'dllimport' attribute}}
>> +
>> +
>> // External linkage is required.
>> __declspec(dllimport) static int StaticGlobal; //
>> expected-error{{'StaticGlobal' must have external linkage when declared
>> 'dllimport'}}
>>
>> @@ -128,14 +135,20 @@ __declspec(dllimport) void redecl3(); //
>> void redecl3() {} // expected-warning{{'redecl3'
>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>>
>> void redecl4(); // expected-note{{previous
>> declaration is here}}
>> +void useRedecl4() { redecl4(); }
>> __declspec(dllimport) void redecl4(); // expected-error{{redeclaration of
>> 'redecl4' cannot add 'dllimport' attribute}}
>>
>> +// Allow with a warning if the decl hasn't been used yet.
>> + void redecl5(); // expected-note{{previous
>> declaration is here}}
>> +__declspec(dllimport) void redecl5(); // expected-warning{{redeclaration
>> of 'redecl5' should not add 'dllimport' attribute}}
>> +
>> +
>> // Inline redeclarations are fine.
>> -__declspec(dllimport) void redecl5();
>> - inline void redecl5() {}
>> +__declspec(dllimport) void redecl6();
>> + inline void redecl6() {}
>>
>> - void redecl6(); // expected-note{{previous
>> declaration is here}}
>> -__declspec(dllimport) inline void redecl6() {} //
>> expected-error{{redeclaration of 'redecl6' cannot add 'dllimport'
>> attribute}}
>> + void redecl7(); // expected-note{{previous
>> declaration is here}}
>> +__declspec(dllimport) inline void redecl7() {} //
>> expected-warning{{redeclaration of 'redecl7' should not add 'dllimport'
>> attribute}}
>>
>> // External linkage is required.
>> __declspec(dllimport) static int staticFunc(); //
>> expected-error{{'staticFunc' must have external linkage when declared
>> 'dllimport'}}
>>
>> Modified: cfe/trunk/test/SemaCXX/dllexport.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/dllexport.cpp?rev=216619&r1=216618&r2=216619&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/dllexport.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/dllexport.cpp Wed Aug 27 16:27:40 2014
>> @@ -53,7 +53,7 @@ __declspec(dllexport) extern int GlobalR
>> int GlobalRedecl2;
>>
>> extern int GlobalRedecl3; //
>> expected-note{{previous declaration is here}}
>> -__declspec(dllexport) extern int GlobalRedecl3; //
>> expected-error{{redeclaration of 'GlobalRedecl3' cannot add 'dllexport'
>> attribute}}
>> +__declspec(dllexport) extern int GlobalRedecl3; //
>> expected-warning{{redeclaration of 'GlobalRedecl3' should not add
>> 'dllexport' attribute}}
>>
>> // External linkage is required.
>> __declspec(dllexport) static int StaticGlobal; //
>> expected-error{{'StaticGlobal' must have external linkage when declared
>> 'dllexport'}}
>> @@ -186,10 +186,10 @@ __declspec(dllexport) void redecl2();
>> void redecl2() {}
>>
>> void redecl3(); // expected-note{{previous
>> declaration is here}}
>> -__declspec(dllexport) void redecl3(); // expected-error{{redeclaration of
>> 'redecl3' cannot add 'dllexport' attribute}}
>> +__declspec(dllexport) void redecl3(); // expected-warning{{redeclaration
>> of 'redecl3' should not add 'dllexport' attribute}}
>>
>> void redecl4(); // expected-note{{previous
>> declaration is here}}
>> -__declspec(dllexport) inline void redecl4() {} //
>> expected-error{{redeclaration of 'redecl4' cannot add 'dllexport'
>> attribute}}
>> +__declspec(dllexport) inline void redecl4() {} //
>> expected-warning{{redeclaration of 'redecl4' should not add 'dllexport'
>> attribute}}
>>
>> // Friend functions
>> struct FuncFriend {
>> @@ -200,8 +200,8 @@ struct FuncFriend {
>> };
>> __declspec(dllexport) void friend1() {}
>> void friend2() {}
>> -__declspec(dllexport) void friend3() {} // expected-error{{redeclaration
>> of 'friend3' cannot add 'dllexport' attribute}}
>> -__declspec(dllexport) inline void friend4() {} //
>> expected-error{{redeclaration of 'friend4' cannot add 'dllexport'
>> attribute}}
>> +__declspec(dllexport) void friend3() {} //
>> expected-warning{{redeclaration of 'friend3' should not add 'dllexport'
>> attribute}}
>> +__declspec(dllexport) inline void friend4() {} //
>> expected-warning{{redeclaration of 'friend4' should not add 'dllexport'
>> attribute}}
>>
>> // Implicit declarations can be redeclared with dllexport.
>> __declspec(dllexport) void* operator new(__SIZE_TYPE__ n);
>>
>> Modified: cfe/trunk/test/SemaCXX/dllimport.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/dllimport.cpp?rev=216619&r1=216618&r2=216619&view=diff
>>
>> ==============================================================================
>> --- cfe/trunk/test/SemaCXX/dllimport.cpp (original)
>> +++ cfe/trunk/test/SemaCXX/dllimport.cpp Wed Aug 27 16:27:40 2014
>> @@ -75,7 +75,7 @@ __declspec(dllimport) extern int GlobalR
>> extern int GlobalRedecl3; //
>> expected-warning{{'GlobalRedecl3' redeclared without 'dllimport' attribute:
>> previous 'dllimport' ignored}}
>>
>> extern int GlobalRedecl4; //
>> expected-note{{previous declaration is here}}
>> -__declspec(dllimport) extern int GlobalRedecl4; //
>> expected-error{{redeclaration of 'GlobalRedecl4' cannot add 'dllimport'
>> attribute}}
>> +__declspec(dllimport) extern int GlobalRedecl4; //
>> expected-warning{{redeclaration of 'GlobalRedecl4' should not add
>> 'dllimport' attribute}}
>>
>> // External linkage is required.
>> __declspec(dllimport) static int StaticGlobal; //
>> expected-error{{'StaticGlobal' must have external linkage when declared
>> 'dllimport'}}
>> @@ -224,10 +224,10 @@ __declspec(dllimport) void redecl3(); //
>> void redecl3() {} // expected-warning{{'redecl3'
>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>>
>> void redecl4(); // expected-note{{previous
>> declaration is here}}
>> -__declspec(dllimport) void redecl4(); // expected-error{{redeclaration of
>> 'redecl4' cannot add 'dllimport' attribute}}
>> +__declspec(dllimport) void redecl4(); // expected-warning{{redeclaration
>> of 'redecl4' should not add 'dllimport' attribute}}
>>
>> void redecl5(); // expected-note{{previous
>> declaration is here}}
>> -__declspec(dllimport) inline void redecl5() {} //
>> expected-error{{redeclaration of 'redecl5' cannot add 'dllimport'
>> attribute}}
>> +__declspec(dllimport) inline void redecl5() {} //
>> expected-warning{{redeclaration of 'redecl5' should not add 'dllimport'
>> attribute}}
>>
>> // Friend functions
>> struct FuncFriend {
>> @@ -240,8 +240,8 @@ struct FuncFriend {
>> __declspec(dllimport) void friend1();
>> void friend2(); // expected-warning{{'friend2'
>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>> void friend3() {} // expected-warning{{'friend3'
>> redeclared without 'dllimport' attribute: previous 'dllimport' ignored}}
>> -__declspec(dllimport) void friend4(); // expected-error{{redeclaration of
>> 'friend4' cannot add 'dllimport' attribute}}
>> -__declspec(dllimport) inline void friend5() {} //
>> expected-error{{redeclaration of 'friend5' cannot add 'dllimport'
>> attribute}}
>> +__declspec(dllimport) void friend4(); // expected-warning{{redeclaration
>> of 'friend4' should not add 'dllimport' attribute}}
>> +__declspec(dllimport) inline void friend5() {} //
>> expected-warning{{redeclaration of 'friend5' should not add 'dllimport'
>> attribute}}
>>
>> void __declspec(dllimport) friend6(); // expected-note{{previous
>> declaration is here}} expected-note{{previous attribute is here}}
>> void __declspec(dllimport) friend7();
>>
>>
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